Tone arm



R. DALLY Sept. 42, 1941.

TONE ARM Filed April 29, 1940 WKNNJ /M LW z/y Nw mi e@ a ,@N, Y. @2^ yNNI Patented Sept. 2,1941

TONE ARM Roy Daily, Racine, Wis., assignor to Webster Electric Company,Racine, Wis., a corporation of Delaware Applicationnprn 29,1940, semina.ssazczf '7 Claims.

The present invention relates to tone arms and is particularly concernedwith improved 'constructions of the tone arm and the supportingarrangements whereby the tone arm is secured to a fixed support forengagement with a record on a turntable.

One of the objects of the invention is the provision of an improved tonearm adapted to beused for sound reproduction apparatus -oi high on thephonograph, to such a position that the Y bottom of the pickup can beinspected and the needle can be most conveniently inserted.

Another .object of the invention is the provision of an improved tonearm support having a resilient connection between the tone arm and thesupport so that the tone arm can be removed at any time by merelyspringing apartv the bearing springs which are carried by one of'theseparts.

Another object of the invention is the prol vision of an improved tonearm supporting structure by means of which undesirable vibrationalcharacteristics of the tone arm or needle noise may be absorbed toprevent the transmission of undesirable vibrations to the stylus of theneedle and the pickup device carried by the tone arm.

Another object of the invention `is the provision of an improvedconstruction for supporting a tone arm, by means of which the tone armis permitted to vibrate as a unit,` thus reducing the resonant frequencycharacteristics which are present whenever an arm vibrates in torsion.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawing in which similarcharacters of reference indicate the, same parts throughout the severalviews.

Referring to the single sheet of drawings accompanying thisspecification:

Fig. k1 is a fragmentary plan view of a phonograph'installation showingthe relation of the tone arm and the record on the turntable;

Fig. 2 is a full size vertical sectional view taken on the planeof theline 2--2 of Fig. 1 looking in the direction of the' arrows, partiallybroken away to show the interior structure of the tone i arm support;

Fig. 3 is another fragmentary vertical sectional viewtaken on the planeof the line 3 3 of Fig. 2 looking in the direction of the arrows; and

Fig. 4 is a fragmentary horizontal sectional view taken on the plane ofthe line of Fig. 2.

Referring to Figs. 1 and 2, il) indicates the supporting structure of aphonograph which is provided with the usual turntable indicated at ilcarrying the phonograph record disc i2. I3 indicates a tone armconstructed according to the present invention and supported upon thebase il! for substantially universal pivotal movement, in order that itmay be raised from or lowered to the record and in order -that it maymove horizontally across the face of the record as the playing of therecord progresses. The base i0 is preferably provided with a specialtone arm support it located at one side of the turntable il and adaptedto support the tone arm wooden screw. I6 and having a verticallyextending column Il. The top of the column Il 'is provided with asubstantially V-shaped notch I8 adapted to receive the stem ISof aheaded mem'- ber 2G carried :by the side of thetone arm.

The headed member 20 has its stem I9 provided with rivetedformationsinside and outside the adjacent wall 2l of the tone arm I3. Thesupporting post 22 for the tone arm is preferably lso located withrespect to the stylus 23 and with respect to the direction Ain which thestylus points, that there is substantially tangential.

be chamfered atl 21, leaving only an annularthrust surface 28 of reducedarea for permitting rotation with a minimum amount of friction.

The lower end of the post 22 ispreferably of reduced diameter andthreaded at 29, leaving an annular shoulder 36 for engagement with awasher or thrust plate 3|. The. post 22 may be secured to the woodenbase l by means of another washer 32 and a nut 33 which clamps the boardI0 between the washers 3| and 32. supporting post 22 rotatably supportsa hollow shaft 35 which comprises a cylindrical tubular brass member,the bore of which is utilized to pass the conductors 36 and 31 whichlead to the pickup unit 38.

Tubular shaft 35 may be provided at its lower end with an annular groove40 (Fig. 3) of substantially semi-circular cross-section adapted toreceive the spring wire 4| which ts in the groove 40 and forms a thrustbearing for the lower end of the shaft 35 to retain the shaft in thepost 22. That part of the spring wire 4I which projects from the groove40 engages the annular thrust surface 42 on the lower end of the post 22when the shaft 35 is actually subjected to any lifting force. As amatter of actual practice, this would only occur when the phonographwere turned upside down or subjected to unusual movements and thus thetoneI arm customarily rests upon the thrust surface 28 and the wire 4Iserves the purpose of maintaining the parts in permanent assembly.

The upper end of the tubular shaft 35 is preferably subjected to anupsetting operation which produces an annular rib 45 having the upperand lower substantially flat surfaces 46 and 41. The surface 46 servesas a thrust bearing engaging the bearing surface 28 on the post 22. Thetubular shaft. 35 is also preferably formed with a partially sphericalprotuberance 48 immediately above the flange 45 and after assembly withthe cushion member 49, it is also formed with an outwardly spun ange 50outside a metallic washer 5|. The cushion member 49 preferably consistsof a soft resilient annular member having, before its assembly with theparts of Figure 3, a cylindrical through-bore 55. It also has thesubstantially flat end surfaces 56 and 51 and its outer surface may besubstantially circular in cross-section at 58, 59. The annular cushionmember 49 is provided with an annular groove 66 of substantiallyrectangular cross-section located in its periphery midway between theends 56, 51, and adapted to receive the adjacent parts of a metal pintleplate 6I.

The pintle plate 6| is shown in Figure 4 and. Figure 2. It comprises arelatively thick sheet metal member, the main body of which issubstantially rectangular in shape, being provided with thesubstantially straight edges 62, 63 and with a substantially circularend boundary 64. At its opposite end, it tapers inward at 65 and 66 andthe relatively narrow end portion 61 is bent upward at 66. The extremeend 69 of this pintleplate is adapted to serve as a stop for engaginginside the upper wall 10 of the tone arm I3 to prevent the stylus 23from `engaging the base I0 when the tone arm is at one side of therecord. This is, of course, also prevented by the supporting column I1when the tone arm is on the supporting column.

The pintle plate 6| has at one end (the right end in Figure 4) acircular aperture 1| which isvslightly smaller than the diameter of thebase 12 of the groove 66 in the cushion member 49.

The thickness of the plate II is substantially the same as the width ofthe groove 60.

Thus, the cushion member 49 may be placed CTI inside the aperture 1| insuch manner that its flanges 1 3 and 14 are located below and above thepintle plate 6I. The cushion member 49 and the pintle plate 6| may thenbe placed upon the partially spherical formation 48 of the tubular shaftand secured in place by means of the washer 5I which is held in place bythe spun formation 50. The space between the washer 5I and the flange 45is such that the cushion member 49 is placed under a predeterminedcompression so that the pintle plate is resiliently gripped by thecushion member 49 and the cush ion member 49 also resiliently grips thepartially spherical formation 48 on the shaft 35. The relation of allthe parts surrounding the cushion member 49 is such that the cushion isplaced under compression and the pintle isresiliently supported upon theshaft 35 but out of all metallic contact with the shaft.

The pintle plate 6| is provided with a pair of laterally projectingportions 16, 11 which are also subjected to an upsetting operation forthe purpose of forming the substantially frusto-conical pintle surfaces18. These pintle surfaces bear such a relation to the bearing apertures19, one of which is located in each wall 2| or 80 of the tone arm, thateach aperture receives one of the pintles 16, 11.

The cushion member 49 also supports the tone i arm in such manner thatit is permitted to vibrate as a unit. This reduces the resonantfrequency characteristics of the tone arm which are present whenever atone arm is vibrated in torsion.

The size of the apertures 19 is such that the inner edge of eachaperture engages on the' frusto-conical wall 18 of the pintles 16, 11.The length of the pintle plate 6| axially of the pintles 16, 11 is suchthat the side walls 2| and 86 of the tone arm are placed underpredetermined tension when the parts are in the position of Figure 3.Furthermore, the two walls 2| and 80 may be forced apart to permit theremoval of the pintle plate 6| by producing a disengagement of one orthe other of the pintles 11 fromA its aperture 19. Thus the tone arm isremovable from the vertical shaft 35 at al1 times. The frusto-conicalpintles are adapted to have an annular line contact with the apertures19 in the tone arm so that they permit movement in a giertical planewith a minimum amount of fric- The tone arm I3 preferably consists of astamped sheet metal member of channeled form provided with an integraltop wall 10 and a pair of parallel side walls 2| and 80. The side walls2| and 80 are joined by an integral end wall 6| (at the right in Figure2) and with an integral end wall 82 (at the left end in Figure 2).Referring to Figure 1, the tone arm I3 is preferably provided with achanneled formation I3 extending diagonally backward from the end 32 andterminating in an end wall 84. This channeled formation is for thepurpose of receiving and locating a crystal reproducer unit 95 of thetype shown in my prior application, Patent No. 2,197,967, issued April23, 1940, Sound reproducing apparatus, and indicated at |45 in Fig. 8 ofthat patent, at such an angle to the main body of the tone arm I3 thatsubstantially tangential tracking may be secured. The present tone armmay, however, be used with any type of reproducer unit such aselectro-magnetic reproducer units or crystal reproducer units. Thecrystal unit may be secured in place by means of a pair of anglebrackets, onel angle bracket 86 being spot-welded to the top wall of thetone arm and having a downwardly extending iiange 8l and a horizontallyextending iiange 88. Anothersimilar angle bracket may have a horizontalnange 88 secured to the flange 88, a side ange Q0, and va horizontalclamping flange 9| which engages the crystal unit 85 and holds it in thetone arm when the flanges 88, 89 are secured together.`

The conductors 38 and 3i are secured in the channeled tone arm i3 byytheir attachment at one end to the crystal unit 85 and at the other endby passing into the hollow shaft 35.' In between these points there maybe spot-welded bendable metal clips 92 which may engage and support theconductorsf and 3l. The circuit preferably includes a signal lightindicating when the circuit is energized and the light may be exposedthrough an 'aperture in the tone arm i3 which is covered with 'atransparent button 93 of a phenolic condensation composition.

The cushion member "i9 is preferably made of pure para rubber of softresilient characteristics or it may be made up out of printers rollcomposition peculiary adapted to prevent the transmission of undesirablevibrations from the support i@ tothe tone arm I3. The tone arm i3 Abelifted high enough so thatl the needle aperture may be inspected and theneedle most conveniently inserted. The arm supporting structure issimple and adapted to take up wear and to prevent rattling and there isa complete absence of metal-to-metal contact between the y tone arm andits metallic supporting post car-` ried by the base of the phonograph orother device. 1

While I have illustrated a preferred embodiment of my invention, .manymodifications may be made without departing from the spirit of theinvention, and I do not Wish to be limited to the precise details ofconstruction set forth, but

desire to avail myselfof all changes within the,

scope of the appended claims. y

Having thus describedmy invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. In a tone arm, the combination of a support with a bearing memberextending transversely to said support, a shaftv rotatably mount ed insaid bearing member and having means at each end retaining it in saidbearing member, a resilient cushion member carried by said shaft,a'pintle plate carried by said cushion member and having oppositelyextending trunnions, and a tone arm having bearings engaging saidtrunnions, whereby said tone arm is supported for substantiallyuniversal movement on said supf port, said cushion member absorbing andproto said support, a shaft rotatably mounted in said bearing member andhaving means at each end retaining. it in said bearing member, aresilient cushion member carried by said shaft, a pintle plate carriedby said cushion member and having oppositely extending trunnions, and atone arm having hearings engaging said trunnions, whereby said tone armis supported for substantially universal movement on said sup. port,said cushionmember absorbing and preventing transmission of undesirablevibrations from said support to said tone arm, a pair of annularcompression members carried by said shaft, said cushion membercomprising a soft, resilient, annular rubber member compressed betweensaid two annular compression members on said shaft and having aperipherally located annular groove for receiving the adjacent parts ofsaid pintle plate.

43. In a tone arm, the combination of a support with a metallic bearingmember having a cylindrical bore and a reduced threaded cylindricalportion with thrust members carried at each end of said threaded portionand threaded means whereby the bearing may be clamped on the support, atubular shaft member rotatably mounted in said cylindrical bore in saidbearing, removable means at one end of said shaft for retaining it insaid bearing, an annular flange carried by said shaft at the other endof said bearing, said bearing having a reduced annular thrust surfaceengaging said ange, a ,thrust member,a resilient rubber cushion memberof annular shape clamped between said nange and said thrust membercarried by the end of said shaft, a pintle plate carried by said cushionmember, and a tone arm carried by said pintle plate for pivotalmovement, said cushion member having an annular groove formed in itsperiphery and said pintle plate having an aperture of a size adapted toreceive that portion of the cushion member at the base of said groove.

4. In a tone arm, the combination of a support with a metallic bearingmember having `a cylindrical bore and a reduced threaded 'cylindricalportion with thrust members carried at each end of said threaded portionand threaded means whereby the bearing may be clamped on the support, atubular shaft member rotatably mounted in said cylindrical bore in saidbearing, removable means at one end of said shaft for retaining it insaid bearing, an annular nange carried by said shaft at the other endofsaid, bearing, said bearing having a reduced annular thrust surfaceengaging said flange, a thrust member, a resilient rubber cushion memberof annular shape clamped ybetween said nange and said thrust membercarried by the end of said shaft, a pintle plate carried by said cushionmember, and a tone arm carried by said pintle plate for pivotalmovement, said cushion member having an annular groove formed in itsperiphery and said pintle plate having an aperture of a size adapted toreceive that to a predetermined compression for the purpose ofpreventing transmission of predetermined vithrough bore, said tubularmetal member being tween said two annular compression members on f witha bearing member extending transversely brations from said bearing tosaid tone arm.

5. A mounting for tone arms comprising a tubular metal member having anaxially extending formed on one end with an annular shoulder and areduced threaded portion, threaded means carried by said reducedthreaded' portion' for clamping the said tubular metal member on asupport,

said tubular metal member having thrust bearing surfaces at each of itsends, a tubular shaft rotatably mounted in said through bore and havingmeans at its lower end for engaging the adjacent thrust surface on saidtubular metal member, said tubular metal shaft having an annular thrustflange projecting at substantially right angles to its axis and locatedat the upper end of said tubular metal member, a live resilient rubberbushing member carried by the upper end of said tubular shaft and havingan annular groove located in its periphery, a compression member carriedabove said cushion member, said tubular shaft being spun outwardly toretain said compression member, and a pintle plate located in saidannular groove, said pintle plate having oppositely projecting pintleswith frusto-conical bearing surfaces located thereon. Y

6. A mounting for tone arms comprising a tubular metal member having anaxially extending through bore, said tubular metal member being formedon one end with an annular shoulder and a reduced threaded portion,threaded means carried by said reduced threaded portion for clamping thesaid tubular metal member on a support, said tubular metal member havingthrust bearing surfaces at each of its ends, a tubular shaft rotatablymounted in said through bore and having means at its lower end forengaging the adjacent thrust surface on said tubular metal member, saidtubular metal shaft having an annular thrust flange projecting atsubstantially right angles to its axis and located at the upper end ofsaid tubular metal member, a live resilient rubber bushing member`carried by the upper end of said tubular shaft and having an annulargroove located in its periphery, a compression member carried above saidcushion member, said tubular shaft being spun outwardly to retain said4compression member, and a pintle plate located in said annular groove,said pintle plate having oppositely projecting pintles withfrusta-conical bearing surfaces located thereon, said live resilientcushion member being placed under a predetermined state of compressionbetween said thrust flange and said compression member whereby thepintle plate is resiliently clamped between the'walls of said groove.

7. In a tone arm, the combination of a supporting post with a shaftrotatably mounted in said shaft, said shaft having laterally projectingand oppositely disposed trunnions carried by its upper end and achannelled tone arm, said tone arm having downwardly projecting flangeson each side, said anges being provided adjacent one end of the tone armwith apertures for receiving said trunnions, and said tone arm beingformed at its free end with a diagonally extending housing portion, anda reproducer member located in said diagonally extending housingportion, said housing portion and reproducer being arranged at such anangle that there is substantially tangential tracking of the needlecarried by the reproducer in the grooves of the record substantiallymidway between the beginning and end groove of the record.

ROY DALLY.

